It is undoubtedly hard to imagine the pilot flying the plane you're on may not fully understand how the automated flight systems in the cockpit work.
"It's disturbing and that's what new details in the Asiana crash suggest," reports CNN's Rene Marsh.
The pilot of an Asiana Airlines jet that crashed in San Francisco this year told investigators after the accident that he had been "very concerned" about landing without help from an airport navigation system that was out of order.
Capt. Lee Kang Kuk, who was highly experienced in a Boeing 747 but was transitioning to flying a 777, told the National Transportation Safety Board that he found it "very stressful, very difficult" to land without the glideslope indicator that helps pilots determine whether the plane is too high or too low during approach.
"Asked whether he was concerned about his ability to perform the visual approach while piloting Asiana Flight 214, he said 'very concerned, yea,'" the safety board revealed at a hearing on Wednesday on its investigation into the July 6 crash that killed three people and injured more than 180 others.
The jet struck a sea wall and broke apart on the runway following a missed approach.
The navigation aid that syncs up with aircraft instruments was out of service while the Capt. Lee Kang Kuk made runway safety improvements. But a second, visual lighting system was operable at the time of the daytime crash and the weather was clear.
The safety board investigation is focusing on whether pilots have become overly reliant on automation to fly commercial planes, and whether basic manual flying skills have eroded.
Investigators have also focused on the pilot understanding - or misunderstanding - of the plane's auto-thrust system, which controls aircraft power.